<p align="center"><b>Show-to restrictions</b></p>

<p>You can restrict access to students with the given permissions. Permissions are
expressed as strings or space-separated list of strings. (These are SAMS authids.)</p>

<ul>
<li>If the field is blank, every student has access.</li>
<li>If more than one permission string is given, users only need one or other of the strings
to obtain access.</li>
<li>Editing teachers (and possibly in some cases ordinary teachers) always have access
regardless of this field.</li>
</ul>